Langerhans Cell Histiocytosis (aka Eosinophilic granuloma, Histiocytosis X (H - X), Hand - Schuller - Christian disease, Letterer - Siwe disease)

General: May be found in any of numerous locations or be multicentric (bone, lung, lymph nodes, pituitary, skin, spleen, etc.). Multicentric cases have lung involvement in ~20% of cases, while ~50% of all cases involve only the lung. Often associated with pneumothorax and/or Pneumocystis carinii pneumonia. Lung disease usually stabilizes or resolves, but ~15% progress to respiratory failure.

Gross:

Microscopic:

Differential Diagnosis: Eosinophilic pleuritis, reactive Langerhans cells in inflammatory conditions, desquamative interstitial pneumonitis

Stains:

• Positive: CD1a+, S100+, HLA-DR+
• Negative:
• Suggested, focused panel:

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